A flexible display device has a configuration in which electro-optical elements are sandwiched, along with circuits that drive the electro-optical elements, other circuits and the like, between a support body that supports these circuits and various functional layers.
The flexible display device is used as a foldable display device that has a flexibly deformable display portion, that is thin and light, and that is bendable.
The above-described electro-optical element includes, for example, an EL element, which is an optical element that utilizes the electroluminescence (hereinafter referred to as EL) of a luminescent material. An EL display device using the EL element is attracting attention as a display device having a faster response speed and a wider viewing angle than a liquid crystal display device.
However, this type of optical element is typically susceptible to the influence of moisture, oxygen and the like, and when a reaction occurs with small amounts of moisture or oxygen, the characteristics thereof are degraded, and reliability deteriorates, thus resulting in a reduced lifetime of the display device.
As a method to suppress the infiltration of moisture and oxygen into the optical element, a method is known in which the optical element is sealed by a sealing film that includes an organic layer.
For example, in PTL 1, a thin film encapsulation (TFE) technology is disclosed in which the above-described optical element is sealed by forming a sealing film, in which inorganic layers (inorganic sealing layers) and organic layers (organic sealing layers) are alternately layered, on the optical element.
Further, in PTL 2, a solid sealed type organic electroluminescent panel is disclosed that is produced by forming, as a stopper pattern that stops the flow of a liquid resin, a plurality of protrusions, which are formed by patterning an insulating layer, in order to configure a bank that partitions a light emitting layer, thus sealing an organic film including the light emitting layer using the resin (an organic sealing layer). Note that in PTL 2, in order to improve the quality of the solid sealing, it is disclosed that a layer of an inorganic material may also be formed on the layer formed of the above-described resin.